Radio frequency and millimeter wave (RF/mmW) imaging has been proven a highly effective component of non-invasive screening for human carriers of explosives, weapons and contraband. The performance of first generation scanners is limited, however, by high capital and operational costs; vulnerability to simple countermeasures; image artifacts and limited resolution due to obscuration and subject pose; and lack of target specificity. The use of mechanically scanned transceiver arrays results in limited update rate as well as large size and high cost. Mechanically scanned arrays are inherently higher maintenance sensors than a fully electronic solution.
Conventional imaging strategies may be segmented into confocal and Fourier designs. A confocal system scans targets point by point. Fourier systems use plane wave illumination to scan frequency space point by point. Both of these approaches are highly inefficient in terms of time and equipment usage. Modern imaging strategies treat image formation as a coding challenge, under which illumination and sampling geometry are programmed to maximize information transfer within temporal and geometric limits.
In view of the foregoing, there is a need for improved imaging systems and techniques.